Resin joint, channel block, and fluid control device

Abstract

A resin joint includes a joint body having a flow path, sleeves, and union nuts that fix tubes to the joint body. The joint body has a body portion with a curved inner peripheral surface and a straight portion protruding from an end portion of the body portion. The straight portion has outer and inner cylindrical portions radially arranged inside the outer cylindrical portion. An end portion of the inner cylindrical portion is positioned closer to the body portion than is an end portion of the outer cylindrical portion. A groove portion extending parallel with the outer and inner cylindrical portions in an axial direction is formed between an inner peripheral surface of the outer cylindrical portion and an outer peripheral surface of the inner cylindrical portion. The tube is fixed to the joint body such that a press-fit portion of the sleeve is press-fitted in the groove portion.

The invention claimed is: 
     
       1. A resin joint comprising:
 a resin joint body having a flow path; 
 a sleeve having a press-fit portion that is press-fittable in the joint body and a coupling portion that is press-fittable in a tube; and 
 a union nut to be attached to an outer periphery of the joint body to fix the tube, in which the coupling portion is press-fitted, to the joint body, wherein:
 the joint body has a body portion with a curved inner peripheral surface and a straight portion protruding from an end portion of the body portion, 
 the straight portion has an outer cylindrical portion and an inner cylindrical portion arranged inside the outer cylindrical portion in a radial direction, the outer cylindrical portion and the inner cylindrical portion having a common shaft, 
 an end portion of the inner cylindrical portion in an axial direction is positioned closer to the body portion than an end portion of the outer cylindrical portion in the axial direction is to the body portion, 
 an inner peripheral surface of the inner cylindrical portion is curved with a curvature equal to that of an inner peripheral surface of the body portion, 
 a groove portion extending parallel with the outer cylindrical portion and the inner cylindrical portion in the axial direction is formed between an inner peripheral surface of the outer cylindrical portion and an outer peripheral surface of the inner cylindrical portion, and 
 the tube is fixed to the joint body in a state in which the press-fit portion of the sleeve is press-fitted in the groove portion. 
 
 
     
     
       2. The resin joint of  claim 1 , wherein the joint body is formed by injection molding. 
     
     
       3. The resin joint of  claim 1 , wherein the end portion of the outer cylindrical portion in a shaft direction on a center-of-curvature side of the body portion is located inside a circle whose center is the center-of-curvature of the body portion and whose radius is a curvature radius of the inner peripheral surface on the center-of-curvature side of the body portion. 
     
     
       4. The resin joint of  claim 1 , wherein the flow path is formed by the inner peripheral surface of the body portion and the inner peripheral surface of the inner cylindrical portion, and
 the length of the inner peripheral surface on a center-of-curvature side of the flow path is ¼ of the circumference of a circle whose radius is the curvature radius of the inner peripheral surface on the center-of-curvature side of the flow path. 
 
     
     
       5. A fluid control device comprising:
 a valve body; and 
 a joint formed with the flow path for supplying fluid to the valve body, wherein: 
 the joint includes the resin joint of  claim 1 . 
 
     
     
       6. A fluid control device comprising:
 a valve body; and 
 a joint formed with the flow path for supplying fluid to the valve body, wherein: 
 the joint includes the resin joint of  claim 2 . 
 
     
     
       7. A channel block comprising:
 a resin block body having a flow path; 
 a sleeve having a press-fit portion that is press-fittable in the block body and a coupling portion that is press-fittable in a tube; and 
 a union nut to be attached to an outer periphery of the block body to fix the tube, in which the coupling portion is press-fitted, to the block body, wherein:
 the block body has a body portion with a curved inner peripheral surface and a straight portion protruding from one end portion of the body portion, 
 the straight portion has an outer cylindrical portion and an inner cylindrical portion arranged inside the outer cylindrical portion in a radial direction, the outer cylindrical portion and the inner cylindrical portion having a common shaft, 
 an end portion of the inner cylindrical portion in an axial direction is positioned closer to the body portion than an end portion of the outer cylindrical portion in the axial direction is to the body portion, 
 an inner peripheral surface of the inner cylindrical portion is curved with a curvature equal to that of an inner peripheral surface of the body portion, 
 a groove portion extending parallel with the outer cylindrical portion and the inner cylindrical portion in the axial direction is formed between an inner peripheral surface of the outer cylindrical portion and an outer peripheral surface of the inner cylindrical portion, and 
 the tube is fixed to the block body in a state in which the press-fit portion of the sleeve is press-fitted in the groove portion.